Who checks your mail and gets payments in hand???

Why is it that you can cash checks all day long but when you get a large payment you can't do sh*t? Who is the person that checks the mail and applies the payments? THAT is the only person I need to talk to. I mailed $2600 to City of Industry CA and it is still on their desk apparently becasue it has not been applied to our accounts nor has it been returned to sender. So someone is sitting on $2600 and doesn't seem to understand how payments from businesses are handled and that we can't just shell out another $2600 via Credit Card because your payment processing department doesn't know how to do their GD JOB!  I am so fed up with Comcast and see why every single one of my residents opts for different service and steers clear of Comcast. I'm ready to cancel all 4 business accounts due to the inability to property process a PAYMENT.